This invention relates to a balance weight attachment system for vehicle wheels and is particularly suited for use with wheels of the full face type wherein a disk face is, joined to a partial formed rim.
Such a wheel is the subject of U.S. Pat. No. 5,360,261, which is incorporated herein by reference. FIG. 1 illustrates a wheel of the type disclosed in that patent, with the wheel indicated generally at 10. The wheel 10 includes an axially outboard full face wheel disk 11, and an axially inboard partial wheel rim 12.
The wheel disk 11 includes a centrally disposed pilot opening 13 and a plurality of apertures 14 disposed thereabout. The apertures 14 receive the mounting studs (not illustrated) which extend from the vehicle wheel hub (not illustrated). The wheel disk 11 may include a plurality of spokes 15 or other structures which define a plurality of through openings (not shown). The openings assist in ventilation of the vehicle brake assembly (not shown). However, aesthetic consideration will commonly dictate the particular configuration of the visible outboard portion of the wheel disk 11, and various spoke designs, solid disk designs, basket weave designs, and the like are common.
The wheel disk 11 further includes an annular portion 17 which includes an outboard tire bead retaining flange 18 and an outboard bead seat 19. An axially extending annular flange 20 is formed on inboard side of the annular portion 12. The flange 20 forms an outboard deep well side wall 21 and an outboard portion 22 of a deep well 23. A lightener groove 24 may be formed in the annular portion 17 of the wheel disk 11 to reduce the weight and inertia of the wheel disk 11.
The partial wheel rim 12 includes an inboard tire bead retaining flange 25, an inboard bead seat 26, an inboard deep well side wall 27, and a cylindrical inboard portion 28 of the deep well 23. With the partial wheel rim 12 and the wheel disk 11 held in co-axial alignment, they may be joined together by forming a circumferentially continuous weld 29 between the inboard portion 28 of the deep well 23 and the outboard portion 22 of the deep well 23, thereby forming the wheel 10. The weld 29 may be formed by such processes as gas metal arc welding or electron beam welding.
After a tire 33 is mounted on the wheel 10; a check is made of the balance of the combined tire and wheel assembly, indicated generally at 34. If the assembly 34 is out of balance, premature and abnormal wear of the tire 33 may result. Additionally, such a condition may cause a rough ride for the vehicle (not shown) on which the wheel 10 is mounted. Traditionally, balancing of the assembly 34 is done statically, by placing the assembly 34 onto a balance (not shown), noting the direction of tilting of the assembly 34, and fixing a balance weight 35 onto the wheel 10 as required to bring the assembly 34 back to a level (balanced) condition. A large number of the retail tire outlets in this country, if not a majority of such outlets, use the static balancing method when mounting tires onto wheels. Another method of balancing the assembly 34 which may be used is dynamic balancing, which will be further discussed below.
Various kinds of balance weights 35 may be fixed to the wheel 10 to bring the assembly 34 into balance. For example, the balance weight 35 may be of the type commonly in use, having a body made of lead which is cast onto a steel spring clip 36. The body of the balance weight 35 is fixed to the outboard face of the outboard tire bead retaining flange 18. The spring clip 36 extends about the radially outer edge to the inboard face of the outboard tire bead retaining flange 18 to grip the outboard tire bead retaining flange 18, and hold the body of the balance weight 35 against the outer face of the outboard tire bead retaining flange 18. Another type of balance weight which is known are stick-on balance weights. Stick-on balance weights 38 have an adhesive backing for fastening the balance weights 38 to the radially inner surface of the wheel well 27 or other accessible, axially extending surface, as indicated in phantom line in FIG. 1. However, stick-on balance weights have proved to be unreliable, in that the adhesive frequently fails and allows the balance weights to come loose, unbalancing the tire and wheel assembly 34.
Affixing the balance weight 35 to the outboard tire bead retaining flange 18 brings the tire and wheel assembly 34 into static balance. However, the axial offset from the balance weight 35 to the center of gravity of the tire and wheel assembly 34 can create a force couple which causes the tire and wheel assembly 34 to shake and the tire 33 to wear unevenly when the tire and wheel assembly 34 is rotated in operation. To reduce the force couple created, the total weight to be added will often be divided in half, with a first half of the weight being in the form of balance weights 35 fixed to the outboard tire bead retaining flange 18, and the remainder of the weight in the form of balance weights 37 fixed to the inboard tire bead retaining flange 25.
As indicated above, dynamic balancing is another type of balancing which may be performed on the assembly 34. In dynamic balancing, the assembly 34 is rotated and the force and direction of imbalance is noted. The balance weights 35 and 37 are clipped to the outboard tire bead retaining flange 18 and the inboard tire bead retaining flange 25 at the locations calculated to bring the assembly 34 into dynamic balance. The balance weights 35 and 37 may be of different weight, as calculated to cause the net effect of the balance weights 35 and 37 to result in a minimal unbalancing force couple. While dynamic balancing results in the assembly 34 operating more smoothly, with less vibration or abnormal tire wear, the equipment to perform dynamic balancing is relatively expensive, and thus is not universally used.
Regardless of whether the assembly 34 is balanced statically or dynamically, clipping the balance weights 35 to the outboard tire bead retaining flange 18 or the stick-on balance weights 38 to any portion of the outboard face of the wheel 10 is objectionable for a number of reasons. Surface pitting of the wheel 10 in the area of attachment of such balance weights frequently occurs due to galvanic corrosion between the dissimilar metals of the wheel 10 and such balance weights. Such corrosion is objectionable due to the adverse effect on the aesthetic appearance of the outboard face of the wheel 10. Furthermore, conspicuously attaching such balance weights to the outboard face of the wheel 10 is objectionable, because the mere presence of the conspicuous balancing weights 35 or 38 would also detract from the aesthetic appearance of the wheel 10. Thus it would be desirable to be able to avoid clipping or adhering balance weights onto the outboard face of the wheel 10.